The present invention is related to a catalytic composition and to hydrocarbon conversion processes employing that catalytic composition. More particularly, it is related to an improved catalytic composition for the reforming of petroleum hydrocarbon feedstocks and to reforming processes utilizing such catalytic composition.
Group-VII-metal-containing catalysts have been employed on a commerical scale in a wide range of reactions, most of them involving hydrogenation, dehydrogenation, oxidation, isomerization, and dehydrocyclization. Especially successful has been the use of alumina-supported platinum catalysts in the conversion of low-octane petroleum naphthas under hydroforming conditions into gasolines of high anti-knock rating. In a typical platinum-hydroforming process, a mixture of charging stock and hydrogen-containing gas is passed through a bed of platinum-alumina-halogen catalyst containing between about 0.05 to 2% by weight of platinum. The hydroforming reactions are carried out at a temperature in the range of about 800.degree. F. to 1,000.degree. F., a total pressure between about 50 pounds per square inch gauge (psig) and 1,200 psig, a recycle gas rate within the range of about 2,000 standard cubic feet per barrel of charging stock (SCFB) to about 10,000 SCFB, and a weight hourly space velocity (WHSV) between about 0.5 and 10 weight units of hydrocarbon per hour per weight unit of catalyst. Hydrogen makes up more than 50 volume percent of the hydrogen-containing recycle gas used therein.
The reforming or hydroforming of various hydrocarbon fractions simultaneously effects a group of reactions, including the production of 6-membered ring naphthenes from other naphthenes by isomerization, dehydrogenation of naphthenes to form aromatics, cyclization of paraffins to form aromatics, isomerization of straight-chain paraffins to form branched-chain paraffins, cracking of paraffins to carbon and to unsaturated fragments of lower molecular weight, hydrogenation of carbon and of the unsaturated fragments, and various side reactions. All of these reactions tend to produce products containing motor-fuel fractions of improved anti-knock rating.
The activity and selectivity of hydrocarbon conversion catalysts depend upon a variety of factors, such as the identity and condition of the catalyst components, the mode of catalyst preparation, the presence or absence of promoters and modifiers, the presence or absence of contaminating materials in the charging stock and the proportion thereof, the conversion temperature, the hydrogen partial pressure in the conversion zone, and the like. Suitable catalysts are conveniently prepared by commingling a Group VII metal compound with a hydrous adsorbent refractory inorganic oxide, such as alumina, and thereafter drying and calcining. A new catalyst composition has now been discovered which affords a hydrocarbon conversion catalyst of greatly improved catalytic properties.